Screen printer with variable frame stroke

ABSTRACT

A device enabling the preset carriage stroke of a silk-screen printing machine to effect the resultant stroke of the screen support frame according to any desired ratio. Transmission gear means effect this desired resultant stroke and comprise gear racks mounted on the carriage and a carrier bar for the screen support frame and three gear wheels mounted on two spindles on a fixed support, the single gear wheel meshing with the gear rack on the carriage, the other two gear wheels meshing with the single gear wheel and the gear rack on the carrier bar respectively.

United States Patent [1 1 Dubuit 1 Oct. 2, 1973 [54] SCREEN PRINTER WITHVARIABLE 3,249,043 5/1966 Karlyn ct a1. 101/]24 FRAME STROKE 3,139,8247/1964 Derrickson 101/124 3,139,823 7/1964 Landesman 101/124 [76]lnventor: Louis Gilbert Dubuit, 60 rue vin'uvev Paris France PrimaryExaminer-Robert E. Pulfrey 2 Filed; 23 9 Assistant Examiner-R. E. SuterAppl. No.: 173,963

Foreign Application Priority Data Sept. 9, 1970 France 7032714References Cited I UNITED STATES PATENTS 2/1955 Gattuso t. 101/38 R X3/1964 Dubuit Attorney-Robert J. Patch 5? ABSTRACT A device enabling thepreset carriage stroke of a silkscreen printing machine to effect theresultant stroke of the screen support frame according to any desiredratio. Transmission gear means effect this desired resultant stroke andcomprise gear racks mounted on the carriage and a carrier bar for thescreen support frame and three gear wheels mounted on two spindles on afixed support, the single gear wheel meshing with the gear rack on thecarriage, the other two gear wheels meshing with the single gear wheeland the gear rack on the carrier bar respectively.

6 Claims, 4 Drawing Figures PATENTED UB7 2l 73 SHEET 10F 2 1 SCREENPRINTER WITH VARIABLE FRAME STROKE BACKGROUND OF THE INVENTION Thepresent invention concerns a device for adjusting the stroke of thescreen support frame of silk-screen printing machine.

It is known that printing machines using silk screens and a squeegee forapplying ink on objects to be printed comprise mechanical means adaptedto provide the screen or the squeegee with reciprocating longitudinalmovement while the other of the screen or squeegee is fixed in thelongitudinal direction.

In the case of printing on flat objects, the screen is fixed and thesqueegee effects reciprocating movement along the surface of the screencausing the ink to pass through the screen onto the article.

In the case of printing on articles with curved surfaces in particularcylinders, the silk screen must pass tangentially to the article to beprinted, the article being held so that its axis is in the horizontalposition while the squeegee is maintained in a fixed position parallelto the axis of the article.

However, the maximum length of the printing surface along the plane ofthe silk screen is generally substantially equal to the stroke of thereciprocating movement of the mechanical element driving the screen;therefore, the possibilities of a machine of this type are limited tothis stroke.

It follows that in order to print on larger threedimensional surfaces,it is necessary to have a machine with greater dimensions. Other thanbeing bulkier, such a machine is more expensive.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a machine capable of printing on bodies with curved surfaces, inparticular cylinders having a predetermined maximum diameter comprisinga device adapted to cooperate with this machine for producing thedesired printed image length irrespective of the maximum path ofmovement of the mechanism carriage of the machine.

French Pat. No. l,332,l2l discloses a device which doubles the path ofmachines comprising a carriage or the like reciprocably displaceablealong rolling or sliding paths or tracks.

The device according to the present invention is not only capable ofdoubling the path but also may produce any desired ratio such as 1.5 -23-5, in order to effect the required length of the printed image.

This device essentially comprises twocantilevered or overhangingmembers, preferably adjustable at two extreme positions on the carriageor the like reciprocating'in a horizontal plane, cantilevered memberseach having a group of rollers for supporting and guiding a carrier barfor carrying the screen support arms or frame.

This group of rollers comprises a roller having a horizontal axis whichcarries the carrier bar and two rollers with vertical axes forhorizontally guiding the carrier bar. Further, another roller having ahorizontal axis fixed on the overhanging members to an eccentric spindlewhich enables a force to be exerted on the carrier bar in order toposition it vertically.

A gear rack is fixed on the rear surface of the carrier bar withvertical teeth.

- wheels are fixed.

A gear rack also having vertical teeth is fixed on the carriage of themachine.

On one of the vertical spindles of the fixed support is mounted forrotation a first gear wheel which meshes with the gear rack on thecarriage, on the other vertical spindle, a second gear wheel meshes withsaid first gear wheel mounted for rotation with a third gear wheel whichmeshes with the gear rack fixed to the carrier bar.

It is easily understood that from the ratio of the first gear wheel onthe said spindle and that fixed onthe other spindle as well as thediameter of the third gear wheel fixed to the second spindle, thedesired multiplication of the stroke of the carrier bar for the screensupport arms or frame versus the stroke of the carriage will beobtained.

STATEMENT OF INVENTION Thus the invention comprises a device foradjusting the stroke of a screen support frame of a silk-screen printingmachine for printing on articles with curved mounted on the carriage andsubstantially parallel thereto, vertical and horizontal guiding meansarranged on arms mounted on the carriage and extending substantiallyperpendicular to the longitudinal axis thereof, a carrier bar forsupporting the screen support frame mounted on the guiding means formovement in a path of travel substantially parallel to the path oftravel of the carriage, a second gear rack mounted on the carrier barand extending substantially parallel thereof, and a housing supporting agear train of exchangeable, replaceable gear wheels in mesh between thefirst and second gear racks, so that the ratio of the stroke of thecarriage to the stroke of the carrier bar may be varied by changing theresultant ratio of the gear train. The guiding means comprise rollerswith horizontal axes for supporting the carrier bar and the horizontalguiding means comprise rollers with vertical axes for guiding thecarrier bar. The rollers with horizontal axes are eccentrically mountedfor adjusting the pressure exerted on the carrier bar. The first andsecond spindles are supported on the housing, and the gear traincomprises a first gear wheel mounted on the first spindle, and secondand third gear wheels mounted on the second spindle, and the first gearwheel meshing with the first gear rack and with the second gear wheel,and the third gear wheel meshing with the second gear rack. The housingis mounted at the center of the machine on the fixed support, and thespindles are parallel to each other. The stroke of the carrier baris'greater than the stroke of the carriage. The arms bearing the guidingmeans are mounted at the extreme ends of the carriage, and at least oneof the arms bearing the guiding means is adjustably mounted on thecarriage.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described hereinafterin greater detail with reference. to the accompanying drawings in which:

FIG. 1 shows a perspective view of the device according to the inventionwith partial cut-away portions;

FlG. 2 shows a partial cross section of the device in FIG. 1 along thelines ll-II of this Figure;

FIG. 3 shows a view in cross section taken along a line lll-lll of thefixed support with the gear transmission means; and

FIG. 4 shows a view in transverse section taken along the line lV-lVshowing the holding of the carrier bar.

DESCRIPTION OF A PREFERRED EMBODIMENT In a embodiment given by way ofexample, the device is mounted on a machine comprising a carriage 1adapted for reciprocating movement by pneumatic or mechanical means (notillustrated). The carriage has two vertical arms 2 and 2 slidable alongcylindrical horizontal bars 3 and 3 and carries a horizontal plate 4.Two overhanging or cantilevered members and 5 are fixed to the plate 4for carrying the carrier which supports the screen support arms orframe. These (overhanging or) cantilevered members 5 and 5' respectivelycarry first rollers 7 and 7 adapted to support the carrier bar 6vertically as well as two sets of rollers 8-9, 8'9 which guide thecarrier bar 6 horizontally. Finally, two other rollers 18 and 18'mounted on eccentric spindles carried by cantilevered members5,5 enablethe bar to be guided vertically.

The eccentric'mounting of the rollers 18,18 enables the adjustment ofthe pressure exerted on the carrier bar 6. The rollers 8-8, 9-9 engagethe upper portions of the carrier bar 6 for lateral guiding; furtherrollers 30,30 act in cooperation with strips 31,31 at the lower portionof the carrier bar 6, also a gear rock 10 is fixed on the rear face ofthe carrier bar 6 for horizontal guiding. A gear rack 11 is also fixedon the horizontal plate 4 of the carriage 1.

A fixed support 12 is mounted at the center of the machine and carriestwo vertical spindles l3 and 14.

A gear wheel 15 is mounted for rotation at the lower end of the spindlel3 and meshes with the gear wheel 16 fixed for rotation on the verticalspindle 14 a third gear wheel 17 also on the spindle 14 also meshes withthe gear rack 10 on the carrier bar 6. The carrier bar 6 carries twoscreen support'arms 19 (only one shown) which are fixed thereto by meansof two plates 20 (only one shown) which may be secured on the carrierbar 6 at various points in order to accomodate various screen lengths,in particular, by means of slot and bolting means as shown in FIG. 1.

It is easily understood that with the ratios between the diameters ofthe gear wheels 15 and 16 and the diameter of the control gear wheel 17assuming the displacement of a unit of carriage of the machine, thecarrier bar may be displaced 1.5-2.5 thereby providing each requiredratio. For example if the diameter of the gear wheel 15 is 60 mm, thediameter of the gear wheel 16 is 20 mm, Le. a ratio of 3 to l and thediameter of the gear wheel 17 is also 20 mm, the carrier bar will bedisplaced three times the displacement of the carrige without thedevice.

It should be noted that each one of the gear wheels may be removed andreplaced by other gear wheels in order to obtain any desired ratiobetween the stroke of the carriage 1 and the stroke of the carrier bar6.

It is also understood that by displacing the carriage l in the samedirection as the carrier bar 6, the overhang of the carrier bar 6 beyondthe cantilevered members 5,5 will be reduced. 1

The present application is not intended to be limited to the illustratedembodiment, but includes all modifications, alternatives and equivalentswithin the scope of the appended claims.

I claim:

1. A device for adjusting the stroke of a screen support frame of asilk-screen printing machine for printing on articles with curvedsurfaces, comprising a fixed support, a carriage mounted on the fixedsupport for movement along the longitudinal axis of the carrige, a firstgear rack mounted on the carriage and substantially parallel thereto,vertical and horizontal guiding means arranged on arms mounted on thecarriage and extending substantially perpendicular to the longitudinalaxis thereof, a carrierbar for supporting the screen support framemounted on said guiding means for movement in a path of travelsubstantially parallel to the path of travel of the carriage, a secondgear rack mounted on the carrier bar and extending substantiallyparallel thereto, said fixed support supporting a gear train ofexchangeable, replaceable gear wheels in mesh between the said first andsecond gear racks, so that the ratio of the stroke of the carriage tothe stroke of the carrier bar may be varied by changing the resultantratio of said gear train.

2. A device according to claim 1, wherein the vertical guiding meanscomprise rollers with horizontal axes for supporting the carrier bar andthe horizontal guiding means comprise rollers with vertical axes forguiding the carrier bar.

3. A device according to claim 2, wherein some of said rollers withhorizontal axes are 'eccentrically mounted for adjusting the pressureexerted on the carrier bar. 7

4. A device according to claim 1, wherein first and second spindles aresupported on said fixed support, and wherein said gear train comprises afirst gear wheel mounted on said first spindle, and second and thirdgear wheels mounted on said second spindle, said first gear wheelmeshing with said first gear rack and with said second gear wheel, andsaid third gear wheel meshing with said second gear rack.

5. A device according to claim 1, wherein the stroke of the carrier baris greater than the stroke of the carriage.

6. A device according to claim 1, wherein the arms bearing the guidingmeans are mounted at the extreme longitudinal ends of the carriage.

1. A device for adjusting the stroke of a screen support frame of asilk-screen printing machine for printing on articles with curvedsurfaces, comprising a fixed support, a carriage mounted on the fixedsupport for movement along the longitudinal axis of the carrige, a firstgear rack mounted on the carriage and substantially parallel thereto,vertical and horizontal guiding means arranged on arms mounted on thecarriage and extending substantially perpendicular to the longitudinalaxis thereof, a carrier bar for supporting the screen support framemounted on said guiding means for movement in a path of travelsubstantially parallel to the path of travel of the carriage, a secondgear rack mounted on the carrier bar and extending substantiallyparallel thereto, said fixed support supporting a gear trAin ofexchangeable, replaceable gear wheels in mesh between the said first andsecond gear racks, so that the ratio of the stroke of the carriage tothe stroke of the carrier bar may be varied by changing the resultantratio of said gear train.
 2. A device according to claim 1, wherein thevertical guiding means comprise rollers with horizontal axes forsupporting the carrier bar and the horizontal guiding means compriserollers with vertical axes for guiding the carrier bar.
 3. A deviceaccording to claim 2, wherein some of said rollers with horizontal axesare eccentrically mounted for adjusting the pressure exerted on thecarrier bar.
 4. A device according to claim 1, wherein first and secondspindles are supported on said fixed support, and wherein said geartrain comprises a first gear wheel mounted on said first spindle, andsecond and third gear wheels mounted on said second spindle, said firstgear wheel meshing with said first gear rack and with said second gearwheel, and said third gear wheel meshing with said second gear rack. 5.A device according to claim 1, wherein the stroke of the carrier bar isgreater than the stroke of the carriage.
 6. A device according to claim1, wherein the arms bearing the guiding means are mounted at the extremelongitudinal ends of the carriage.